The ease with which a connection can be made and broken is important in the ultimate usability of a connector technology. For example, screw-type connectors having threaded connections and deformable gaskets are strong, tight and can generally withstand high pressures. However, such connectors are labor-intensive to break and reform, and upon reformation, the quality of the reconnection is generally inferior to the quality of the original connection. Also presently on the market are flange-type connectors requiring an annular gasket for sealing. When functioning, the gasket is generally partially embedded in the surface of each flange. It is usually formed either entirely of an elastomeric material, or of a rigid plastic, with an additional layer of elastomeric or other deformable material at least partially overlying and adhering to the upper and/or lower annular surface of the gasket or the flange at the point of flange/gasket contact.
One problem with presently existing connection designs is their performance under high pressure and aseptic conditions. High-pressure conditions are frequently encountered in closed circulating systems, where pressures can be as high as 110 psi. Aseptic systems are frequently encountered in food science, food preparation, biological laboratories, as well as other applications. Connections presently on the market are susceptible to breach and leakage due to the failure of the gasket to maintain a seal. Bacterial contamination often breaches them from the outside, and fluids under high pressure can breach them from within.
Many existing connector designs have other problems as well. One issue which arises is the issue of cost. For every connection, at least two, and often three differently designed parts must be manufactured. For instance, many designs require that the connection be comprised of two halves having complementary designs such that they interlock or otherwise fit together to form the connection. As indicated above, such designs generally require the presence of a gasket to complete the seal. The gasket spans a space between the halves, nesting in a recess, generally annular, in the surface of each connector. Three different pieces are required for completion of the seal: a left connector, a right connector, and a gasket. In some designs, the connectors do not have a “handedness,” designed instead such that the connection can be completed by two identical pieces. Such a design requires connector pieces and a gasket piece. Whether or not the connector halves are identical, a separate gasket is still generally required to complete the seal.
In order to efficiently form a seal between the rigid gasket and the connector piece, it is generally necessary that the gasket be of a deformable material or, if the gasket is of a rigid material, that a layer of deformable material be disposed over the surfaces of the gasket and/or within a retaining recess on the connector flange. One structural feature linked to the failure of gasket-containing connectors at high pressures or stringent aseptic conditions is the failure of the elastomeric gasket or deformable sealing layers between the gasket component and the connector pieces.
In order to elucidate the problem, it is necessary to have a degree of understanding of the mechanics of sealing and gasket failure. Many screw and other type connections move the connectors toward each other while rotating them about their cylindrical axes with respect to each other in order to form a seal. Thus rotation occurs while elastomeric surfaces are in contact, and further rotation increases the pressure between the surfaces, increasing the frictional forces between them, preventing them from slipping and relieving the stress introduced by rotation. As a result, upon completing the connection, the elastomeric components of the gasket, whether they comprise the entire gasket, or only a layer between a rigid gasket component and a flange, have “stored” energy in elastic deformation.
The axial components of the strain can be useful in forming the seal; deformation in the axial direction introduced by forcing sealing members together generally results in a countering, axially-directed urge within the elastomeric portions of the sealing assembly, enhancing sealing ability of the completed seal.
However, components of stress parallel to the surface of the sealing layer, such as circumferential and radial components, can be efficiently converted to axial pulls which 1) counteract the axial forces pressing the sealing components together and 2) result in pressure differentials across the surfaces of the seal, enabling the formation of channels between the interior and the exterior of the seal, through which breaches can occur.
One example of this type of conversion is caused by rotating, in opposite directions, two elastomeric faces which are pressed into mutual contact. The elastomeric face is part of an elastomeric disk which is immobilized at the contact face as well at as its anchoring face. Rotation causes the entire elastomeric disk to tend toward a slight flattening with increasing angular distance from the starting configuration. Ideally, the axial pull is uniform with angle and radius over the sealing surface, but in reality, even slight asymmetries due to manner of contacting to complete the seal, distribution of forces due to and during operation, forces due to external buffeting, and the like cause the pressure across the sealing surface to tend strongly toward nonuniformity, if not immediately upon sealing, upon operation. A contributing factor to such a failure is the storage of stresses (introduced upon, for example, completing the seal) in the gasket and connector sealing layers which cause the layers to deform such that the bias to return to their original configurations destroys the uniformity of contact pressure over the surfaces forming the seal interface. With a loss of uniformity, channeling, or the existence, transiently or permanently, of low pressure regions connecting the interior and the exterior of the seal, occurs.
Designs having closing strategies circumventing axial rotation (such as connector halves which are attached at an edge point such that they can be folded into mutual facing contact) also have the problem of the stored stresses counterproductive to sealing. The act of closing the halves over a gasket can result in stored stresses which are essentially unidirectional in the direction of closing. Such stresses can be expected to reduce the integrity of the seal, having circumferential as well as radial components, both of which are parallel to the surface of the sealing layer.
Furthermore, stresses which bend the cylindrical axis of the assembly at the seal redistribute pressure across the face of the seals and cause breaching. Such a scenario is particularly appropriate in situations in which the connectors are plastic and deformable, even slightly.
On the whole, each seal created by pressing together 1) two elastomeric surfaces or 2) an elastomeric and a non-elastomeric surface has associated with it a risk of failure due to channeling mechanisms. For this reason, the presence of elastomeric sealing surfaces is generally thought to raise the risk of breach.
A gasket-type connector with reduced susceptibility to failure would be an advance over the present state of connector art. Furthermore, a gasket-type connector additionally having the convenience of a rotation or axial push engagement would be even more desirable. Moreover, a genderless gasket connector in which the complete connection is simplified with respect to existing connectors in that it can be formed from two identical pieces would be welcomed by the industry.
It should be fully understood that variations of the foregoing disclosure not explicitly described above can be within the spirit of the present invention. For example, connectors comprising sealing members which are not genderless, but which form sealing assemblies comprising two or more stacked gaskets, optionally having different thicknesses are also within the ambit of the present invention. In another example, the present invention includes sealing assemblies in which the gasket bears a projection which nests into a sealing annex on a sealing member, inclusive of assemblies requiring only one gasket for sealing.